feat: update PostgreSQL MCP schema to use DATABASE_URL environment variable

- Add DATABASE_URL argument for prompting user during installation
- Replace hardcoded connection strings with environment variable
- Update both npm and docker installations to use DATABASE_URL
- Follows same pattern as other MCP servers in the registry

Author: zhujian0805

code_assistant_manager/mcp/registry/servers/postgresql.json

@@ -19,15 +19,25 @@
     "name": "modelcontextprotocol"
   },
   "homepage": "https://github.com/modelcontextprotocol/servers-archived/tree/main/src/postgres",
+  "arguments": {
+    "DATABASE_URL": {
+      "description": "PostgreSQL connection string (e.g., postgresql://user:password@host:port/database)",
+      "required": true,
+      "example": "postgresql://localhost/mydb"
+    }
+  },
   "installations": {
     "npm": {
       "type": "npm",
       "command": "npx",
       "args": [
         "-y",
         "@modelcontextprotocol/server-postgres",
-        "postgresql://localhost/mydb"
-      ]
+        "${DATABASE_URL}"
+      ],
+      "env": {
+        "DATABASE_URL": "${DATABASE_URL}"
+      }
     },
     "docker": {
       "type": "docker",
@@ -36,9 +46,14 @@
         "run",
         "-i",
         "--rm",
+        "-e",
+        "DATABASE_URL",
         "mcp/postgres",
-        "postgresql://host.docker.internal:5432/mydb"
-      ]
+        "${DATABASE_URL}"
+      ],
+      "env": {
+        "DATABASE_URL": "${DATABASE_URL}"
+      }
     }
   },
   "tools": [